Systems for remotely guiding vehicles by operator control or in accordance with an automatic guide mechanism which follows a pre-established path have been long known in the art. Remote control systems frequently utilize complex servo mechanisms and other various electronic circuitry. Other systems rely on electronic sensors for detecting guide markers previously implanted in the ground. These largely electronic systems require much cost and maintenance to assure their reliability over extended periods of use. In addition, repair of these units necessitates a person with an electronics background and associated electronic support tools for repair and maintenance. Furthermore, the front end cost of such a guide apparatus is substantial.
It is therefore highly desirable that a guide apparatus be developed which is accurate, rugged and basically mechanical in nature so as to circumvent some of the draw-backs associated with largely electronic systems. In response to this need, mechanical guidance apparatus such as disclosed in U.S. Pat. No. 3,797,602 (Sumida) have been developed. However, while Sumida overcomes many of the problems associated with largely electronic systems, there are many problems associated with Sumida.
Sumida does not disclose an integrated wheel mechanism and trench cutting mechanism. In Sumida, a trench cutting mechanism is shown as being separately attached to the farm implement. The trench cutting mechanism must be extended a substantial distance beyond the side of the implement so that guide trenches for a succeeding path are formed so as to assure there will be no overlap in the area of the field being worked by the implement. This makes the implement more bulky and less easy to maneuver. If the trench cutting mechanism is attached adjacent the side of the implement, there will be substantial overlap of the area of the field being worked by the implement on subsequent passes thereby requiring more passes to work a given field area. Such a configuration would also make Sumida useless in chemical applications where there can be no overlap.
Furthermore, Sumida discloses no apparatus for controlling the operation of the trench cutting mechanism. The trench cutting mechanism is passive in nature and is shown as operatively engaging the ground at all times while the implement is working the field. This requires more pulling power and makes the implement more difficult to control. More ever, Sumida discloses no method for raising the trailing wheel mechanism when so desired.